A3 Assembly Control Circuits; Analog Bus Drivers - HP 8560E Service Manual

A3 Assembly Control Circuits

A digital control problem will cause the following three steps to fail:
1. On the HP 8560E/EC, press
2. A click should be heard after pressing dB in step 1, unless ATTEN
was previously set to 70 dB.
3. Press 1, 0, and
dB
heard, but the ATTEN value displayed on the CRT changed, the
digital control signals are not operating properly.

Analog Bus Drivers

Refer to function block N of A3 Interface Assembly Schematic Diagram
(sheet 4 of 6) in the
HP 8560 E-Series Spectrum Analyzer Component Level
.
Information
1. Press on the HP 8560E/EC, and set the controls as follows:
PRESET
Span .............................................................................. 0 Hz
Trigger ....................................................................... Single
2. Monitor A3U401 pin 3 (LRF_STB) with an oscilloscope or logic
probe. This is the strobe for the A15 RF Assembly.
3. Press and
AUX CTRL
toggling between
4. Monitor U401 pin 5 (LFC_STB) with an oscilloscope or logic probe.
This is the strobe for the A14 frequency control assembly.
5. Press
AMPLITUDE
between settings of 10 and 20 dB.
ATTEN
6. Monitor U401 pin 7 (LIF_STB) with an oscilloscope or logic probe.
This is the strobe for the A5 IF assembly.
7. Press
AMPLITUDE
settings of −10 dBm and −20 dBm.
between
REF LVL
8. Monitor U401 pin 9 (LLOG_STB) with an oscilloscope or logic probe.
This is the strobe for the log amplifier on the A4 assembly.
9. Press
AMPLITUDE
between and
LINEAR
10.To check the Address and Data Lines, place a jumper from A3TP1
and A3TP2 to A3U406 pin 20 (+5 V).
11.Check that address lines A0 through A7 and data lines D0 through
D7 are all TTL high.
Chapter 7
AMPLITUDE
. Another click should be heard. If no clicks were
and check that pulses occur when
REAR PANEL
and
10 MHz INT 10 MHz EXT
and check that pulses occur when toggling
and check that pulses occur when toggling
and check that pulses occur when toggling
.
LOG dB/DIV
ADC/Interface Section

A3 Assembly Control Circuits

, , 7, 0, and
ATTEN MAN
.
.
dB
385